Process of making curved composite glass plates



Allg 22, l933- J. H. sHER-rs ET AL PROCESS OF MAKING CURVE!) COMPOSITE GLASS" PLATES original Filed April 24. 195o 2 sheets-sheet 1 l f, w

dor-1N BY M 7 /Clla/ A TTORNEYS Augn 22, 1933. ;l H sHER-rs Er A| l Re. 18,918

PROCESS 0F MAKING CURVED COMPOSITE GLASS PLATES Original Filed April 24, 1930 2 Sheets-Sheet 2 A TTORNEYS Reissued Aug.v22, 1933 VUNITED STATES l Re. 18,918

5 t; PROCESS 0F MAKING CURVED COMPOSITE I GLASS PLATES James H. Shorts, Brackenrldge,

and John Willits, -Ford City, Pa., assignors to D uplate Corporation, a Corporation of Delaware Original No. 1,815,992, dated July 28, 1931, Serial No. 446,862, April 24, 1930. Application lfor reissue May 2.2, 1933. Serial No. 872,220

s claims. (c1. issn The invention relates t a process of making curved composite glass plates, ordinarily consisting of two glass sheets with an interposed .sheet `of pyroxylin plastic, although' other reinforcing may be used if desired. One field of use for such plates is in the manufacture of goggle lenses and the process isillustrated as applied in such connection, but it will be understood that the bent laminated plates may be used in other relations. The invention has for itsv objects the provision of an improved process which insures vthat the two sheets shall have the same 'curvaturey upon their opposing surfaces, and reduces the breaking incident to compositing under heavy pressure to -a minimum. The steps incident to the practice of the method and the apparatus preferably used are shown in the accompanying drawings, wherein:

` Figure 1 is a verticall section through the kiln and mold in which the glass sheets are bent. Fig. 2 isA a planview of a pair of blanks which have been bent, the dotted lines indicating the lines of cutting in order to produce pairuof -glass sheets from each pair of blanks. Fig. 3 is an end eleva- 4 is a planview of one of the complete gogglf glasses. Fig. 5 is a plan view of one oi' the rubber bags in which the blanks are composited. Fig. 6 is a section through the bag and its contents on the line VI-VI of Fig. 5. And Fig. 'l is a vertical section through the pressure tank in which thel rubber bags are placed in order to subject them to heat -and pressure in the usual way.

Referring to F' 1, 1 is a furnace heated in any suitable manny f is a mold in which the glass sheets 'to be sited are bent; and 3, 4 'are a 4pali' .0f sla rThese sheets a 40 indicated in the drawings in full lines and upon the application of heat, they sink down into the mold 2 to the dotted line position indicated at A. The heat applied in order to secure this result is just sufficient to soften the glass so that the sheets will sink down to the position shown, but is not suicient to cause the sheets to` stick together. After the sheets 3 and 4 have thus been bent so that they fit each other, they are sepairated and a sheet of celluloid, which is to act as the reinforcing, is placed therebetween the celluloid sheet being shown at 5 in Fig. 6. In order to secure the adherence between the glass andl celluloid, a suitable cement, such as gelatin, is employed, or the surfaces of the celluloid are .66 made sticky by the use of a solvent, such as ace- ,be entrapped'betweenl the opposing faces'of theI l sheets. The bag as thus evacuated is now placed tion oi' the pair of blanks shown in Fig. 2. Fig.

which are 'to be composites? IplacedDrie upon the other tone. The three sheets as thus assembled are held together by means ofv proper stickers placed around the edges of the sheets, this being an expedient Well-known in the glass compositing art. The set of sheets as thus assembled is ready for pressing and is placed in a rubber bag 6, as indicated in Figs. 5 and 6, each bag being ofsufilcient size so that it will carry a plurality of the sets of sheets 3 and 4, such sets of sheets being indicated `in dotted lines in Fig. 5. After the sets of sheets T to be composited are placed in the bag 6, a clamp 7 is applied at the end of the bag and the air is exhausted from the bag through the evacuating check valve 8. This exhausting action causes the bag to collapse around the sets of sheets, as indicated in Fig.'6 and withdraws any air which may in a pressure chamber 9 (Fig: 'IY having a re movable cover 10 and pipe connections'll and 12. The compositing in'this pressure chamber now proceeds in theordinary way. That is, thetem.- perature of the liquid in the tank is brought' up to about 240 degrees F. by circulating the lliquid to and'from a heat transfer device' by means of the pipes 11 and 12, after which the pressure Ais increased to .about 150. pounds per 'square inch. After therubber bag and its contents has been exposed to these conditions for a suitable period, ordinarily froml to 15` minutes, the pressure and temperature are reduced. and the rubber bag and its contents are removed from the pressure ch'an-y ber, thus completing the pressing operation. The plates as thus' composited are now remov A the-.bajg-and if goggle blanks-:farete n u u ced, .they ar""f`cut,.asidicatedln N tr-lenses beit :infirm-mh ff this particular-.fcaii,theseI t v inches longandf-4 inches size of the cui therefrom a being dependent upon conditions and requirements. It is, of course, possible to cut the sheets of glass and celluloid to size, as indicated in Fig.- 4, before compositing,l but this is a somewhat plates and the numberl of vmore difiicult method of procedure and the danger of-the sheets slipping upon each other lis greater with the small pieces than with the larger ones, such as shown in Figs. 2 and 3.l

The foregoing method -of procedure insures a good product with substantially nobreakage and a minimum of slippage between the sheets during the compositingv action. vThe small amount of breakage is due-n a large measure to .the fact that the opposing glass shee match each other exactly in the matter of curvature which result is due to the fact that the sheets are bent together, one upon the other, as indicated in Fig. l, and heretofore explained. The process is applicable to sheets of any size or shape, the mold 2 being modied as to size and shape in order to meet requirements.

What we claim is: 1. A process of making curved composite glass plates which consists inv supporting two glass sheets which are to form the plate one upon the other above a concave mold, applyingheat suiiicent to make the sheets plastic and causing them to sink into and t the mold, but not sufcient to cause them to stick together, assembling the sheets as thus bent With an interposed sheet of flexible reinforcing material and securing the sheets as thus assembled together.

2. A process of making curved composite glass plates which consists in supporting the two glass sheets which are to form the plate one upon the other above al concavemold, applying" heat sufc'ient to make the sheets plastic and causing them to sink into and t the mold, but not suflicient to cause them to stick together, assembling the sheets as thus bent with aninterposed sheet vof flexible reinforcing material and cementing cient to make the sheets plastic but not suilicient to make them stick together, causing them to bend and fit the mold, assembling the sheets as thus bent with an interposed sheet of flexible reinforcing material, and securing the sheets as thus assembled together.

JAMES H. SHERTS. JOHN WILLITS. 

